1. Technical Field
The present invention relates to a light-emitting device, and more particularly, to a light-emitting element array having an adhesive layer.
2. Description of the Related Art
Light-emitting diodes (LEDs) are employed in a wide variety of applications including optical display devices, traffic lights, data storage equipment, communications devices, illumination apparatuses, and medical treatment equipment. One of the most important goals of engineers who design LEDs is to increase the brightness of the light emitted.
U.S. Pat. No. 6,547,249 discloses monolithic serial/parallel LED arrays formed on highly resistive substrates. According to the patent, a Group III-V nitride light-emitting stack layer is formed on an insulating substrate. A portion of the stack layer is etched away to form a trench, and in result to form the LED array, which includes a plurality of light-emitting diodes divided by the trench. Since the insulating substrate is not conductive, both P-contacts and N-contacts for the LED array have to be formed on the same side of the LED array. In use, two LED arrays can be connected either in series or in parallel. However, the LED array disclosed by the patent cannot be applied to a quaternary AlInGaP light-emitting diode, which comprises a conductive substrate rather than an insulating substrate, P-contacts formed on one side of the conductive substrate, and N-contacts having to be formed on the other side. Therefore, two quaternary Al—In—Ga—P light-emitting diode arrays can be connected neither in series nor in parallel. Moreover, as the size of the LED array become larger, the operating voltage of the LED array becomes higher accordingly, and heat dissipation becomes an important concern for the LED array.